An investigation of dielectric resonator antenna produced from silicon (100) enhanced by strontium doped-barium zirconate films

Dip-coated Ba_1−x Sr _x ZrO₃ thick films with different Ba/Sr ratios (x = 0.0, 0.1, 0.3, 0.5, 0.7 and 0.9) were fabricated on Si (100-orient) substrate at a low temperature of 800 °C via the sol gel method. The experimental results show that dielectric resonator (DR) properties of Ba_1−x Sr _x ZrO₃ films depend on the different Ba/Sr ratios. For structural characterization, the X-ray analysis revealed that phase transformation was affected by the increase in Sr concentrations for heat treatment at 800 °C. The films were crystalline and of single phase. The thickness of one BSZ film is around 1.259 μm when measured using the field emission scanning electron microscope. The BSZ film’s surface morphology as indicated by the atomic force microscopy showed the mean grain size to be in the range of 2.56 to 94.34 μm, and the surface roughness (RMS) was recorded to be between 2.35 to 19.64 nm. The dielectric resonator (DR) properties were measured using a network analyzer. By introducing Ba_1−x Sr _x ZrO₃ (BSZ) films on the high dielectric Si (100-orient) substrate, better frequency stability was achieved i.e. within the range of 8–10 GHz. Measured results show that Si (100-orient) DRA has a 10 dB impedance bandwidth of 4.11% at 9.34 GHz and the BSZ improved this to 11.34% with x = 0.7 at 9.15 GHz. The radiation pattern was observed to be stable throughout the operating frequency and holds good potential for DR applications.     

Profile of Parkia speciosa Hassk Metabolites Extracted with SFE using FTIR‐PCA Method

A rapid identification, classification and discrimination tool, using Fourier Transform Infrared (FTIR) spectroscopy combined with Principal Component Analysis (PCA), was developed and applied to determine the profile of the Supercritical Fluid Extraction (SFE) of Parkia speciosa seeds under various temperature and pressure conditions (313, 323, 333, 343, 353 and 363 K and 20.68, 27.58, 34.47, 41.37, 48.26, and 55.16 MPa). The separation and identification of the compounds was carried out by Gas Chromatography coupled with Time of Flight Mass Spectrometry (GC/TOF‐MS). This technique has made it possible to detect the variability obtained under different SFE conditions and the separation of different chemical compounds in P. speciosa seeds. The FTIR‐PCA results were verified by GC/TOF‐MS, and the FTIR‐PCA method successfully identified the unsaturated carboxylic acids with the highest percentage area under the different conditions.     

Fish Oil Recovery from Viscera of Indian Mackerel (Rastrelliger kanagurta) by Supercritical Fluid: An Optimization Approach

Fish viscera, a waste of fish processing industry, can be exploited as a source of PUFA‐rich fish oil for use in food or pharmaceutical industry and at the same time the environment can be protected from pollution by fish wastes. Fish oil was recovered from viscera of Indian Mackerel (Rastrelliger kanagurta), by different supercritical fluid extraction (SFE) e.g. continuous, co‐solvent, soaking, and pressure swing techniques and the yields were compared with that of the solvent extraction method. The SFE parameters such as pressure, temperature, and CO₂ flow rate were optimised by employing Response Surface Methodology (RSM) with a view to maximize the oil yield and minimize CO₂ consumption. The central composite rotatable design (CCRD) consisting of three variables provided 20 experimental settings. Multiple regressions determined the coefficients of the second‐order polynomial equation. The optimum parameters for all 4 techniques applied were found to be 35 MPa, 60 °C, and 2 mL min^?1 with an Oil recovery ranging from 93 to 99%. The study demonstrated a lower CO₂ consumption by the soaking and pressure swing techniques at the optimized conditions. Thus, the soaking and pressure swing techniques were most effective for extracting oil from fish viscera.     

Raman spectroscopic analyses of preserved historical specimens of human hair attributed to Robert Stephenson and Sir Isaac Newton

The Raman spectra of two historical specimens of human hair attributed to the engineer Robert Stephenson and scientist Sir Isaac Newton, preserved in private collections are reported. Comparisons are made with the Raman spectra of modern hair specimens and with hair from archaeological excavations. The hair spectra collected with a laser excitation of 785 nm are of a better quality than those collected using 1064 nm. The historical hair specimens are remarkably well-defined spectroscopically in terms of the amide I vibrational mode and the [small nu](SS), ascribed to a predominantly gauche-gauche-gauche CSSC conformation. The contrast with degraded hair specimens recovered from archaeological excavations is striking. The presence of a weak feature near 2590 cm(-1) in the hair samples attributed to a [small nu](SH) vibration could be indicative of a reduction process operative on the CSSC cystine keratotic linkages and a possible origin of this is bacterial biodegradation identified histologically. This study demonstrates the molecular information available from non-destructive Raman spectroscopic analysis from single hair shafts or small bundles of fibres which complements information available from histological and destructive analytical techniques for rare biological specimens subjected to conservation or curation procedures in museums or private collections.     

Impact of interfacial composition on emulsion digestion and rate of lipid hydrolysis using different in vitro digestion models

A sequential in vitro model of digestion was used to investigate the changes in the physicochemical properties of emulsions during gastrointestinal transit. Oil-in-water emulsions were prepared with whey protein isolate (WPI) or soy protein isolate (SPI) at the same protein concentration (1.5%). Despite pepsinolysis of both proteins during the gastric phase, emulsions stabilized with WPI were more stable compared to those prepared with SPI. For both emulsions, the size of the oil droplets, which plays a critical role in lipid digestion, was extensively altered during the duodenal phase due to the presence of bile salts (BS) and phospholipids (PL). As shown by ζ-potential measurements, the results suggested the displacement of both proteins from the interface by BS; however, the displacement was much faster for the WPI-emulsions. The change in interfacial composition of the oil droplets was significantly affected by inclusion of PL and phospholipase A(2) (PLA(2)) in the in vitro digestion model. The interfacial activity of pancreatic triglyceride lipase (PTL) was markedly affected in the presence of the surface-active compounds present in the digestive fluids, including BS, PL, colipase (COL) and PLA(2). A higher percentage of lipid hydrolysis was obtained in the presence of COL and PLA(2) than with BS alone or mixed BS-PL. SPI-emulsions consistently showed a higher degree of lipolysis compared to the WPI-emulsions regardless of the in vitro digestion model used. The results support the conclusion that the interfacial composition of the original emulsion plays a major role in determining the extent of lipolysis.     

The Interaction of CORM‐2 with Block Copolymers Containing Poly(4‐vinylpyridine): Macromolecular Scaffolds for Carbon Monoxide Delivery in Biological Systems

CORM‐2, tricarbonyldichlororuthenium(II) dimer (Ru₂Cl₄(CO)₆), is a common carbon monoxide releasing molecule (CORM) studied both in vitro and in vivo, but this compound possesses poor water solubility and a short half‐life, which hinders its clinical development. Herein, for the first time the conjugation of CORM‐2 is reported with a copolymer containing poly(4‐vinylpyridine) to yield water‐soluble CO‐releasing polymeric nanoparticles. CORM‐2 is rapidly conjugated to copolymers through pyridine groups as confirmed by inductively coupled plasma‐optical emission spectroscopy and infrared spectroscopy. In comparison with free CORM‐2, the copolymers functionalized with CORM‐2 display better water solubility and the CO release from the polymer‐based CORM is slow and sustained. This study paves the way for the potential use of a copolymer encapsulating CORM‐2 as a therapeutic agent.

     

Deformation Quantization for Hilbert Space Actions

Rieffel's theory of deformations of C^*-algebras for -actions can be extended to actions of infinite-dimensional Hilbert spaces. The CCR algebra over a Hilbert space H can be exhibited in this manner as a deformation of a commutative C^*-algebra of almost periodic functions on H. Received: 26 August 1996 / Accepted: 28 January 1997